Method of making radiators



Dec. 17, 1935. R. M ccRArrH 2,024,379

METHOD OF MAKING RADIATORS Filed Oct. 24, 1952 Patented Dec. 17, 1935 METHOD OF MAKING RADIATORS Robert McCraith, Lockport, N. r., assignor, by mesne assignments, to General Motors Corporation, Detroit, Micln, a eorporationrof Delaware Application Uctober 24, 1932, Serial No: 639,212

4 Claims. (Cl. 113-113) 'This invention relates toheat exchange devices and more particularly to improved methods of manufacturing cores of the type most commonly used in the radiator of an engine cooling system.

The conventional automobile radiator involves a heat dissipating unit or core interposed between inlet and'outlet tanks and made up, of a number of spaced passages for the flow in thin streams of water or other cooling medium from which heat is transferred through the walls of the passages to air passing through open spaces in the core. The present invention has to do especially with the so-called cellular type of radiator core, which is madeup by passing a narrow'strip of metal, such as'copper or brass, having good heat conducting properties, through a. forming machine to give the desired shape and shear to given length a number of strips, each of which is then bent upon itself in elongated loop fashion about a preformed separator or fin strip, and the opposite ends joined together by a hand soldering operation. The sub-assembly unit thus formed is placed side by side with a number of-similar units, the adjacent walls of adjoining units being nested together in proper spaced relation to constitute water passageways and the whole assembly clamped in a suitable fixture and while so clamped the front and-rear faces successively are dipped first in an-acid solution and then in molten solder, the solder sealing the mating edges of the walls of each passageway and joining the several strips into .a unitary assembly.

I have found that when portions of the metal walls are in continuous and firm contact'transversely of the core, the acid and the solder will flow upwardly for some distance by' capillary attraction between such contacting surfaces at the time the edges are dipped into the acidand solder baths. This flow by capillary attraction is sufiicient to give ta bond and seal entirely across the core, even in the case of a relatively. deep core, since the flow between such surfaces that they will be'joined and sealed-by capillary For a better .understanding of the nature of' the invention, reference is made to the accom-.' panying drawingiliustrating a preferred embodiment and .wherein Figure 1 is a detail perspective view of a sub-assembly unit with one of the 5 walls bent outwardly so as toillustrate to better advantage therelation of the parts; Figure 2 is a perspective view of two sub-assembly units nested together; Figure 3 is a sectional view of w the soldered ends of a wall strip, :the fin strip being omitted for the purpose of clarity, and Figure 4 is a view similar to Figure 3, but illustrating the type of joint produced by .the handsoldering practice followed heretofore.

Referring to the drawing, the reference characters i and 2 indicate a pair of walls or partitions, each of which is intended for cooperation with a corresponding or'complementalwallon a mating sub-assembly unit when placed in side to side relation to afford a water passageway. These two walls ljand Zare a part; of a single preformed strip bent upon itself in looped .formation with an intermediate portion extending laterally between thewalls as at 3 at one end of the loop. The free end of the wall I is bent or turned laterally to form the end portion 4 and then bent back in parallelism with the Well i as at'5. The end of the wall 2 has a part turned laterally as at 6 and is intended to overlap the end 5 and a part of 'the end section 4. It will thus be seen that the end portions of the two walls overlap for a considerable. extent,

and since the irregular surface in one wall mates or corresponds to the contour to the other wall, the overlapping parts will be snugly inter- 3 nested and presentadiacent surfacesin'continuous contact-across the walls and of, considerable width; Within the loop formed by the wall a strip may belocated a separator or fin strip 1 of any suitable configuration, to divide. the 40 intervening air space into a number of small cells and provide heat radiating flns on the walls of adjacent water tubes.

When several ofsuch sub-assembly units are brought together and nested, as are the two units illustrated in Figure .2, the dipping of first one face and thenthe other face of the assembly in a solder bath'will not only seal the frontvand rear edges of. abutting walls, but will result in an inward flow of solder between the contacting aces of the overlapped end portions to secure bond these parts together and prevent any leakage therebetween, 4

- In the exaggerated .view, Figure 3,. there. is illustrated the thin layer a ofsolder between the overlapping end portions and for the purpose of comparison there is illustrated in Figure 4 the type of seal produced by the customary hand soldering operation. The seal in Figure 4 involves a thin bead 9 of solder deposited on the exterior surfaces of the adjoining ends of the outer wall prior to the time the sub-assembly units are placed side by side. This hand solder- I ing operation can be entirely eliminated, thereby 1. The method of forming a radiator, including bending a number of wall strips each into an elongated loop having corrugated sides with the opposite terminal portions extending toward each other in one of said sides and overlapping in nested relation throughout the transverse extent of the strip, assembling side by side the looped strips with their corrugated portions interfitting, and then soldering the overlapping faces by capillary flow.

2. The method of making a heat exchanger including forming a number of sub-assemblyunits each by bending a strip of metal into an elongated lo'op having corrugated sides, with the end portions of the strip in overlapping nested relation, placing a number of such units side by side with their corrugations interfitting and soldering the interfltting faces by capillary flow.

3. The method of making a radiator core, including working a flat strip to provide therein a succession of like formations, bending a given length of the strip into an elongated loop having corrugated side walls adapted to receive therein"a fln strip, with the opposite ends of the strip in overlapping nested relation in one of the side walls of the loopthroughout a length containing several of said like formations, assembling several of such units side by side with the corrugations thereon in interfltting relation and finally dipping opposite faces of the group' of units in solder to join the. units and at the same time seal the overlapped ends of each strip. 90

such units side by side with their corrugations $5 in nested relation, and then joining the units and sealing the joints by capillary flow from molten solder applied to the edges of said walls.

ROBERT MCCRAIYI'H. 

